Messages in this thread Patch in this message | | | From | "Suzuki K. Poulose" <> | Subject | [PATCH] [powerpc] Export memory limit via device tree | Date | Mon, 02 Jul 2012 17:19:00 +0530 |
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The powerpc kernel doesn't export the memory limit enforced by 'mem=' kernel parameter. This is required for building the ELF header in kexec-tools to limit the vmcore to capture only the used memory. On powerpc the kexec-tools depends on the device-tree for memory related information, unlike /proc/iomem on the x86.
Without this information, the kexec-tools assumes the entire System RAM and vmcore creates an unnecessarily larger dump.
This patch exports the memory limit, if present, via chosen/linux,memory-limit property, so that the vmcore can be limited to the memory limit.
The prom_init seems to export this value in the same node. But doesn't really appear there. Also the memory_limit gets adjusted with the processing of crashkernel= parameter. This patch makes sure we get the actual limit.
The kexec-tools will use the value to limit the 'end' of the memory regions.
Tested this patch on ppc64 and ppc32(ppc440) with a kexec-tools patch by Mahesh.
Signed-off-by: Suzuki K. Poulose <suzuki@in.ibm.com> Tested-by: Mahesh J. Salgaonkar <mahesh@linux.vnet.ibm.com> ---
arch/powerpc/kernel/machine_kexec.c | 15 +++++++++++++++ 1 files changed, 15 insertions(+), 0 deletions(-)
diff --git a/arch/powerpc/kernel/machine_kexec.c b/arch/powerpc/kernel/machine_kexec.c index c957b12..0c9695d 100644 --- a/arch/powerpc/kernel/machine_kexec.c +++ b/arch/powerpc/kernel/machine_kexec.c @@ -207,6 +207,12 @@ static struct property crashk_size_prop = { .value = &crashk_size, }; +static struct property memory_limit_prop = { + .name = "linux,memory-limit", + .length = sizeof(phys_addr_t), + .value = &memory_limit, +}; + static void __init export_crashk_values(struct device_node *node) { struct property *prop; @@ -226,6 +232,15 @@ static void __init export_crashk_values(struct device_node *node) crashk_size = resource_size(&crashk_res); prom_add_property(node, &crashk_size_prop); } + + /* memory-limit is needed for constructing the crash regions */ + prop = of_find_property(node, memory_limit_prop.name, NULL); + if (prop) + prom_remove_property(node, prop); + + if (memory_limit) + prom_add_property(node, &memory_limit_prop); + } static int __init kexec_setup(void)
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